Increasing demand for more powerful and convenient data and information communication has spawned a number of advancements in communications technologies, particularly in wireless communication technologies. A number of technologies have been developed to provide the convenience of wireless communication in a variety of applications, in various locations. This proliferation of wireless communication has given rise to a number of manufacturing and operational considerations. In most cases, however, wireless communications systems have at least one common denominator—the need or intent to maximize data transfer rates.
Since wireless communications rely on over-the-air (OTA) transmissions, wireless systems and their operation are subjected to a number of environmental interferences, as well as regulatory requirements and restrictions. These regulatory influences can vary considerably, and even conflict, across different countries or regions. Wireless device manufacturers and service providers often develop industrial standards to define specific communication schemes, and to help reconcile competing or conflicting approaches thereto. Environmental interferences can vary from naturally occurring phenomena to conflicting wireless transmissions. The proliferation of wireless communication has resulted in a number of disparate technologies that may operate in adjacent, partially overlapping, or overlapping frequency ranges or channels. Wireless device manufacturers and service providers must therefore also comprehend potential performance and reliability degradations that may result from frequency range conflicts.
Among recently emerging communication technologies—especially those targeted at or intended for high data transfer rates—various ultra-wideband (UWB) technologies are gaining support and acceptance. UWB technologies are commonly utilized for wireless transmission of video, audio or other high bandwidth data between various devices. Generally, UWB is utilized for short-range radio communications—typically data relay between devices within approximately 30 feet—although longer-range applications may be developed. A conventional UWB transmitter generally operates over a very wide spectrum of frequencies, several GHz in bandwidth. UWB may be defined as radio technology that has either: 1) a spectrum that occupies bandwidth greater than 20% of its center frequency; or, as it is more commonly understood, 2) a bandwidth ≧500 MHz.
UWB systems commonly utilize a modulation scheme, known as Orthogonal Frequency Division Multiplexing (OFDM), to organize or allocate data transmissions across extremely wide bandwidths. OFDM schemes are commonly utilized, not only in UWB systems, but also in high-bandwidth communications systems and protocols such as 802.11(a).
Often, particularly in UWB systems, OFDM schemes are supplemented by dividing a given frequency range into multiple sub-bands. Systems that utilize these multiple sub-bands in combination with OFDM modulation are commonly known as Multi-band OFDM. Multi-band OFDM (MBOFDM) in a UWB system provides relatively low-power, broad-spectrum communication that enables high bandwidth data transfer.
Considering UWB as an illustrative example, the Federal Communications Commission (FCC) of the United States has allocated the spectrum from 3.1 GHz-10.6 GHz for UWB radio transmissions. This UWB frequency allocation is unlicensed, leaving the spectrum open to a number of potentially conflicting technologies. Due to this unlicensed nature, UWB devices and systems have to contend with both pre-existing and future-developed services that occupy adjacent frequency bands or share some portion of the same frequency band. In order to successfully co-exist, UWB systems should be capable of adapting to certain spectral masks—selectively limiting transmissions in certain spectral sub-ranges.
Moreover, the relative strength (i.e., power) of UWB signals is also limited to a transmit power of −41.25 dBm/MHz. Due to this relatively low-power, short-range nature of UWB, even a nominal degree of signal fading or interference from an adjacent frequency band can significantly impact the signal integrity of a given tone.
In the increasingly common situation where a conventional OFDM system (e.g., a UWB system) must account for one or more spectral masking requirements, certain sub-ranges of a frequency band cannot be utilized—decreasing the system's potential data transfer bandwidth. In order to achieve a desired high bandwidth data transfer, over a now-limited available sub-portion of a channel, the conventional OFDM system has to maximize the raw volume of data transferred over the available channel sub-portion. Unfortunately, however, conventional OFDM systems utilize a number of data coding and redundancy techniques for error correction and data integrity purposes. Although these techniques improve the reliability and integrity of data transmissions, by accounting or correcting for signal noise or interference, they reduce effective data transfer bandwidth by significant amounts. Thus, wireless system designers utilizing OFDM techniques may often face a tradeoff between achieving optimally high data transfer rates and ensuring data integrity or reliability.
As a result, there is a need for a system that provides optimal data throughput in OFDM-based communication technology while providing reliable data integrity—one that maximizes system utilization of all available sub-portions of a given wireless transmission frequency range—in an easy, efficient and cost-effective manner.